Why Are Nights So Hot In Delhi, Mumbai, Kolkata? Reason Behind High Minimum Temperatures Explained

Heatwave has gripped large parts of India with hotter than usual nights as minimum temperatures hover around 30 degrees Celsius. The trend has been the same for cities like Delhi, Mumbai, Kolkata, Chennai, Hyderabad and Ahmedabad. These areas are recording minimum temperatures close to or above 30 degrees Celsius at night and in early morning hours.

As per IMD’s latest bulletin, heatwave conditions are very likely to prevail during May 24 to 27 in Delhi. There will be a rise in minimum temperatures by 2-3 degrees Celsius during the next 24 hours, while there will be no large change till May 29 and fall by 4-5 degrees Celsius thereafter.

Temperatures have already exceeded 45 degrees Celsius in many areas of Delhi. Hospitals in the National Capital Region (NCR) are seeing a rise in the number of patients suffering from heat-related illnesses.

Reason Behind Rising Minimum Temperature Explained

Extreme Day Temperatures

As reported by India Today, weather expert Devendra Tripathi said the continuous intense daytime heat across multiple states has been the main reason for the unusually warm nights being witnessed in recent weeks.

“When temperatures remain continuously between 40 degrees Celsius and 45 degrees Celsius for many days, the outgoing long-wave radiation at night is unable to escape efficiently into the atmosphere,” he said as per the report.

“As a result, heat remains trapped both on the land surface and in the air, which keeps the minimum temperature elevated,” he added.

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Role Of Moisture In Air

Tripathi also emphasised the role of increased moisture content in the air. He stated that humid areas tend to suffer more at night since the water layer does not let the heat escape.

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“Moisture creates a layer in the atmosphere that blocks heat from escaping easily,” he said. “Where dry winds prevail, and skies remain clear, temperatures cool faster at night and may fall to 25 degrees Celsius or 27 degrees Celsius. But in humid regions, the heat gets trapped.”